I have phenom ii x6 1090t but when overclocking it to 4 ghz i have to set the cpu voltage to 1.56 which is the maximum volt
to this cpu when i try to reduce the voltage to 1.5 it crashes , i have asus crosshaire iv formula and 8 GB kingstone 1333mhz
y1090 is for the voltage will vary depending on the chip and the system and the motherboard is used, 6 core overclock 4.ghz takes between 1.52v - 1:56, some are getting 1.42v, and I wear a 1050 oc to 4.01 ghz is still safe with vCore 1.52ghz (stable) as long as the temperature below 55C on Prime95 test fulload still safe. but do not use every day, more secure you go to 3.8GHz with 1:42 vCore-.144 and overclock ram
It could just be the processor itself. I could get my 1090 to 4 GHz but it wasnt easy so 3.9 might be the top end for you. In terms of performance, it wont matter cause there is virtually no difference, at least not one that would see in actual use, between 4.0 and 3.9. So unless youre just doing for the fun and the challenge (which is what I do) then might as well leave it at 3.9 with a little lower voltage.
I think the ram is bad because i tried every thing increase cpu-nb voltage and ram voltage but nothing happened
well, your ram definitely MAY be the cause.
But, I wasn't sure on what kind of kingston ram you had. I have Kingston HyperX Blu 8gb 1600 DDR3 (2 sticks), and they do a great job when overclocked slightly. However, I haven't tested it with higher clocks around 1866mhz.
It definitely MAY be your cpu too. I was lucky enough to pick up a nice stable unlockable AMD Phenom II X4 960T and turned it into a X6 1600T overclocked @ 3.8 ghz with about 1.350v with .05v offset.
I can hit 4.0-4.5ghz as a X6 CPU with it but, I haven't taken it that far yet.
Your CPU VCORE voltage should not exceed 1.55v. However, it may be different for your CPU.
if you want to overclock your CPU for best performance and results, you need to consistently test your hardware and see what settings fit best as overclocking results will vary on each PC.
Also, if you're new to overclocking, DO NOT try anything until you get a aftermarket cooler such as the cheap yet, powerful CoolerMaster Hyper 212+.
Run Memtest or something to check if your ram is bad.